Comparative analysis of herpesvirus-common proteins

Excerpt

Despite the evolutionary and biological divergence represented by the nine human herpesviruses that have been classified into three broad subgroups, a large number of herpesvirus-common (core) gene products are evolutionarily conserved (Table 4.1 see chapter 2). These appear to carry out functions upon which every herpesvirus relies because all exhibit a common virion structure, a core genome replication process, and similar entry and egress pathways. These herpesvirus common functions are most often recognized through deduced protein sequence similarity that extends throughout alpha-, beta-, and gammaherpesviruses subfamilies infecting mammals, reptiles and birds (see Chapter 2, Table 2.2). These herpesviruses exhibit conservation that suggests a shared common ancestor at least 50 million years ago. Other evolutionarily distant herpesviruses infecting fish, amphibians, and invertebrates share less similarity with these better-studied herpesviruses, suggesting a common evolutionary origin dating back over 150 million years. In the more distant relatives, a common virion structure, genome organization and similarity across a small subset herpesvirus-common gene products provide the evidence of a common origin.